with \((x_{c}, y_{c})\)  standing for the galaxy center obtained by
minimising the total light [1]}. This parameter in
general has values in the range \(-3 < M20 < 0\) . It is very sensitive to the
spatial distribution of light. For undisturbed early-type
galaxies when the brightest 20% of the light may easily be positioned
close to the galactic center, M20 approaches values of -2.5 or -3.0. On
the other hand, the presence of multiple bright sources of light that
are spatially separated from the galaxy center (e.g., bars, spiral arms,
strong star-forming regions, etc.) increase the value of M20 toward 0
[2]}.
